Buoyed by the success of two robotic rovers exploring the surface of Mars, NASA scientists are building smarter and more- agile robots that can rappel down cliffs, slither between cracks and even have the sense to detect trouble.

Scientist Silvano Colombano stood next to one of the new machines on a recent morning at NASA Ames Research Center in Mountain View, where he demonstrated an eight-legged robot called Scorpion. It can climb up steep hills and plunge into rough terrain where its wheeled counterparts can't go.

Next to Colombano, computer engineer Maria Bualat showed off the K9 rover, a robot similar to the Mars rovers, but one that can perform tasks 10 times faster than its cousins, which have been exploring the Red Planet since early last year.

How about NASA building a lot of these guys and having them look for Osama!